The objective of this project is to establish the precise chemical structure of glycolipids in the following materials: 1) several lines of oncogenic cell lines transformed by viruses or chemicals as compared to untransformed cells. 2) Purified preparations of "normal" glia and neurons isolated from brain. 3) Retina and retinal rod outer segment, a paracrystalline structure derived from the neuronal plasm membrane. The method consists of two steps: First, incubations are carried out in vitro using the material under study as possible source of glycosyltransferases to catalyze the biosynthesis of glycolipids labeled specifically in the glycosyl unit which will act as receptor of the additional glycosyl residue from donor sugar nucleotides. Second, it will then be possible to trace the radioactive receptor unit in the product glycolipid and to establish by the method of permethylation the precise position(s) of the newly formed linkage(s). BIBLIOGRAPHIC REFERENCES: Structure of trihexosylceramide biosynthesized in vitro by rat kidney galactosyltransferase. A. Stoffyn, P. Stoffyn and G. Hauser. Biochem. Biophys. Acta, 360, 174 (1974). P. Stoffyn, A. Stoffyn and H. Shein, Structure of Gangliosides Biosynthesized by C21 Astrocytoma Cells. Presented at the Fifth International Meeting of the International Soc. for Neurochemistry, Barcelona, Spain, Sept. 1975.